Plunger for hypodermic syringes and the like



Nov. 14, 1933. H. 0. WEST PLUNGER FOR HYPODERMIC SYRINGES AND THE LIKEFiled March 20, 1950 Jzye/ Patented Noy- 1933 h I, I i I I b [UN TED S EP TENT-WQF WE PLUNGER FOR HYPODERMIIIIIC SQYRINGEVS,

AND THE LIKE,

-- Herman West, Philadelphia, Pad Application M crame. Serial News); 1Claim. '(Cl. 128-218) This invention relates primarily to improve- Fig.3' ,is a view in perspective illustrating a ments in hypodermicsyringesand more particufurther step in the process of manufacture;larly toimprovements in the rubber plungers Fig. 4 shows a sectionalView of the finished which constitute a standard part of such devices. punger, and

5 In hypodermic syringes it is frequently desir- Figs. 5'and 6 aresectional views illustrating a v able to retract as well as advance theplunger in modification within the scope of the invention.

the syringe cylinder, and for this purpose the In the production of asocket member'in acplungers, commonly of flexible rubber, are cordancewith my invention, I prefer to employ equipped with inserted socketsthreaded or a blank in theform ofa rod 1 of square cross .10 otherwiseformed for interlocking connection section which may be of brass orother suitable with a stem by means of which the plunger may material.In an initial operation, I mayemploy be actuated. Considerabledifiiculty. has been a rotary boring tool, as indicated at '2 in Figs. 1experienced in obtaining an eficient bondbeand 2, which is adapted tSimultaneously O m tween the rubber of the plunger and the socket in theend of the blank 1 a central lon itud al '15 element, and particularlyin the retracting of the Cylindrical recess 3 and an outer Co plunger,the socket elements have been s bject nular recess 4, the latterintersecting the sidev to breaking away from the rubber plunger,surfaces of the blank to form spaced ears or prothereby rendering thesyringe inoperative. The J'ec O S ab y and s st at d, the difficulty isincreased by the fact that frequently portions of the cutter 2 whichform the recess 4 12 0 the plungers stick in the barrel and can be areflared or beveled outwardly a v the Cutting released only by rotatingthe plunger, a moveedge whereby as the cutter advances in the ment whichtends to tear the socket loose from cutting ope the ears P j i 5 are therubber. Another influencing factor resides b nt' u w y awa from e al ynd ical in the fact that the syringe, after being charged p 6, asClearly illustrated- FOllOWihg the d 1 25 with serum or other substanceis usually subing or boring op n as set forth abov h so jected to asterilizing operation at a, relatively socket element is completed yinternally hreadhigh temperature, .this heat effecting chemical in otapp t c cylindricaliopening 3 changes tending to separate the rubberfrom the and by cutting w y the machined extremity of a socket 1ement ndtending l t Cause th the blank 1 to obtain an element substantially as1-30 rubber plunger to adhere to the sides of the illustrated in Thesocket member thus cylinder. produced'is introduced into the mold inwhich Y It is an object of thisihvention to provide an the rubb r plu715 rm d a d isjmelded into improved plunger having astem-receivingsocket e pl W known n r, the fi s ed j so formed and embedded in theplunger as. to art being Shown i Fig;

-':35 effectively resist the tendency of all normal Socket-member 0f t om illu trated and 549 of separation of the socket member andconsestrains and stresses to loosen the socket from described above hasbeen found admira y u ed the surrounding rubber, and thereby to providefor the Q P The base hortlon 0f t mema plunger t may be freely advancedor ber, proJectmg from the sides of the central tracted or rotated inthe cylinder without danger socketed part establishes relativelyextended rubber-abutted surfaces which are normal to the thrusts orstrains exerted through the stem 8 1 I. 'ther advancing or retractingthe plunger in The invention resides not only 1n the plunger I as awhole but in the specific form andmethod of barrel the Syringe i areCapable of l manufacture of the socket insert as hereinafter Standing te forces tendmg toward Separatlon Set forth of. the socket member fromthe rubber. In the i th tt h d d V retraction movement the tongues5-also assist in e i awm anchoring the socket member, and these elementsstreamers retreatin r of member 0 ear oose rom e rubber w en the cedurethe socket member is manufactured, and plunger through t te 3 is tat ith 5, also sh ws a p o of one r of tool that y barrel. This function ofthe tongues 5 is aided be e p y by the flared formation previouslydescribed. Flg. 2 is a View in perspective illustrating the It will benoted that but three operations are initial step in the manufacture ofthe socket required for producing the socket member in the quentdestruction of the syringe.

}55 member; procedure outlined above,-and while. a socketmemberembodying the substantially same desirable characteristics may beproduced by other methods, the one herein described commends itself forits simplicity and relative cheapness. It has also been found that witha tool of the general character illustrated, the longitudinal edges ofthe tongues 5 are rough and uneven which aids in creating a firm bondbetween these elements and the rubber of the plunger.

In Figures 5 and 6, I disclose a socket-member formed of metal tubing.In this instance a blank tube is internally threaded at one end and atthe other end is divided longitudinally by crosscuts to form foursections which are then bent outwardly and back to form elementscorresponding to the tongues 5 of the previously described embodiment.The corresponding parts of V the two embodiments are identified by thesame reference numerals.

I claim:

A plunger for hypodermic syringes comprising a cylindrical body portion,and an integral socket member embedded in said body portion, said socketmember comprising a base and a central socket for the reception of anactuating stem, a substantially rectangular flange on the socket memberprojecting from the base in the plane thereof, and an element at eachcorner of said flange extending laterally therefrom along the socketportion substantially parallel therewith and spaced therefrom wherebyrotational, lateral and axial movements of the socket member within thebody portionare prevented.

' HERMAN 0. WEST.

